Ford Ranger "Thunderbolt"

Can someone tell me the difference between a normal Ford Ranger and the "Thunderbolt" model they were selling a couple years back. A client of mine bought the Thunderbolt for around $23,000 and 2 Ford dealers told her 3 months later that the truck was just an ordinary Ranger not worth more than $17k. I can't find anything out about this model. Blue Book does not have a separate listing for it, like for example the "Eddie Bauer" edition of the Expedition,etc.